Thermodynamic Parameters for the Interaction of Amoxicillin and Ampicillin with Magnesium in NaCl Aqueous Solution, at Different Ionic Strengths and Temperatures

Abstract

In this paper, the sequestering ability of amoxicillin and ampicillin toward Mg 2+ in NaCl aqueous solutions at different ionic strengths I = (0 to 1.0) mol•kg −1 and temperatures of T = (288.15 to 318.15) K was investigated by potentiometry (ISE-H + , glass electrode). The complex formation constants determined at different ionic strengths and temperatures were modeled by means of the Debye−Huckel equation and the Specific ion Interaction Theory (SIT). From the results, a weak ability of the two penicillins to bind the metal ion can be observed; in fact, the stability constants of the ML species (M = Mg 2+ and L = amoxicillin or ampicillin) are log β = 4.348 and 3.242 at infinite dilution and T = 298.15 K, respectively. The dependence of the formation constants on the temperature was modeled by means of a van't Hoff equation, which allowed us to calculate the enthalpy and entropy change values of formation of each species. The sequestering ability of amoxicillin and ampicillin toward Mg 2+ in the different experimental conditions (pH, ionic strength, temperature) was quantified by means of a sigmoid equation and of the pL 0.5 parameter. The pL 0.5 values reflect the low stability constant values of the species; as an example at I = 0.15 mol•kg −1 , pH = 7.4, and T = 298.15 K, we have pL 0.5 = 2.52 and 2.78, for Mg 2+ /amox 2− and Mg 2+ /amp − systems, respectively.

Interaction of Ampicillin and Amoxicillin with Mn2+: A Speciation Study in Aqueous Solution

“…Among these cations, the behaviour of Mn 2+ is quite similar to Mg 2+ and Ca 2+ . More in detail, for the system containing Amp, formation constant values for MgLH and MgL species are 2.54, 2.86, respectively (at I = 0.15 mol L −1 and t = 25 °C) [21], for the same species containing Mn 2+ are 2.47, 2.37, respectively, as reported here under the same conditions. For the system containing Amox, formation constant values for MLH and ML species with Ca 2+ are 2.69, 2.59, respectively (at I = 0.15 mol L −1 and t = 25 °C) [22], for the same species with Mn 2+ are 2.78, 3.20, respectively, as reported here under the same conditions.…”

“…Only formation constant values for Cu 2+ , Ni 2+ , Zn 2+ , Cd 2+ , Co 2+ are found. As far as we know, no thermodynamic data are reported on the complex species formed by Amox with any metal cation, apart from the results already published on Ca 2+ , Mg 2+ , Cu 2+ , Zn 2+ cations [19][20][21][22]. Therefore, it is possible to compare simply the results here reported on Mn 2+ with those obtained with other divalent cations.…”

“…For this reason, the assessment of the interactions of these antibiotics with metal cations which play biological roles in the human body is crucial [18]. Complexing abilities of the most important amino-penicillins, i.e., ampicillin and amoxicillin, with some metal cations, namely Zn 2+ , Cu 2+ , Ca 2+ and Mg 2+ , were already studied [19][20][21][22].…”

The Solution Behavior of Dopamine in the Presence of Mono and Divalent Cations: A Thermodynamic Investigation in Different Experimental Conditions

“…For Mg 2+ , the hydrolytic constants were taken from [33]; whilst for Ca 2+ from [34]. For Sn 2+ , the acid-base properties were already studied in a previous work, from an accurate analysis of literature data and experimental investigations, at different conditions (i.e., I/mol dm −3 , T/K, etc.)…”

Thermodynamic Study on the Interaction of Ampicillin and Amoxicillin with Ca2+in Aqueous Solution at Different Ionic Strengths and Temperatures

“…This paper is part of larger research on the ampicillin ( Amp ) and amoxicillin ( Amox ) acid–base and complexation properties with different metal cations in aqueous solution. − Ligands under study are reported in Figure . In this study, the experimental measurements were performed by two techniques, potentiometry and spectrophotometry.…”